Polysaccharide structures, such as films and fibrous elements, are known in the art. Due to the inherent brittle nature of polysaccharides, structures, such as fibrous elements, made from polysaccahrides exhibit lower than desired strength and/or stretch properties, such as lower than desired dry and wet tensile properties including lower than desired fail total energy absorption (“Fail TEA”) properties and lower than desired elongation (stretch) properties. One known way to increase the strength and/or stretch properties of polysaccharide structures is to add a high molecular weight (greater than 500,000 g/mol) polymer, such as a polyacrylamide, which is a homopolymer, compatible with a polysaccharide-containing composition at a concentration greater than the high molecular weight polymer's entanglement concentration. In fact, fibrous elements, for example filaments, comprising polyacrylamide and fibrous structures comprising such fibrous elements are known in the art. A limitation with this strategy is that molecular weight reduction of the high molecular weight polymer, polyacrylamide for example, easily occurs due to mechanical degradation, during processing, such as occurs as a result of shear forces experienced during processing within an extruder, for example a twin screw extruder. As a result, such fibrous elements and fibrous structures exhibit strength and/or stretch properties which fall short of consumers' expectations for such fibrous elements and fibrous structures employing same. For entanglement purposes, it is desirable to use as high molecular weight polymer as possible in the fibrous elements, but due to the degradation of molecular weight during processing, the molecular weight of the high molecular weight polymer, for example polyacrylamide, in the fibrous elements is limited, typically to about 3,500,000 g/mol or less. Therefore, additional means of increasing the strength and/or stretch properties of the fibrous elements and fibrous structures employing such fibrous elements is needed.
Another known method for increasing the strength properties of polysaccharide structures, such as fibrous elements, is to crosslink the polysaccharides molecules of the polysaccharide structure. However, crosslinking between polysaccharide molecules, such as starch molecules, only provides chemical or covalent interactions between the polysaccharide molecules, but does not promote chain entanglement like synthetic, flexible polymers, such as polyacrylamide.
Accordingly, a problem faced by formulators is how to make fibrous elements, for example filaments, and fibrous structures comprising such fibrous elements, exhibit greater strength and/or stretch properties compared to the known fibrous elements and fibrous structures comprising such fibrous elements described above.
Therefore, there is a need for fibrous elements, for example filaments, and fibrous structures employing such fibrous elements that exhibit improved strength and/or stretch properties compared to the known fibrous elements comprising polyacrylamide and fibrous structures comprising such fibrous elements.